Test Head Positioning System with Compliant Mechanisms
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Solution Overview
Problem
Existing test head manipulator systems face challenges in providing sufficient vertical range of motion and maintaining compliant motion across six degrees of freedom, especially when dealing with larger and heavier test heads, which can be difficult for operators to manually manipulate due to increased physical force requirements.
Innovation Solution
The system employs a combination of support structures and compliant mechanisms, including pneumatic cylinders and spring systems, to provide a broad vertical range of motion and compliant motion about non-vertical axes, allowing for efficient docking of test heads with different peripherals by distributing the load and reducing the manual force needed for manipulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If pneumatic cylinders are used to position and manipulate test heads in the vertical direction, then the vertical stroke is limited by the stroke of the pneumatic cylinder arrangement, but using larger test heads requires a longer vertical range of motion that cannot be practically achieved
Solution Approach 1:
The vertical positioning function is divided into two segments: a long-stroke pneumatic cylinder for coarse vertical positioning and a lead screw mechanism for fine vertical positioning. This segmentation allows the system to achieve a long vertical range of motion while keeping individual components practical in size. The pneumatic cylinder handles the bulk of the travel, while the lead screw provides precision control for the remaining distance.
Solution Approach 2:
The lead screw mechanism acts as an intermediary between the pneumatic cylinder and the test head. It converts rotational motion from the pneumatic cylinder into linear vertical motion, enabling the system to extend the vertical range of motion beyond the physical stroke limit of the pneumatic cylinder while maintaining control and precision.
2Adaptability or versatility
If test heads are made larger and heavier to handle more complex testing tasks, then the manual manipulation becomes more difficult due to increased physical force requirements, but reducing size limits testing capability
Solution Approach 1:
The system employs pneumatic cylinders that generate upward force to counteract the weight of the test head. By balancing the pneumatic pressure against the gravitational force, the test head is maintained in a substantially weightless condition, allowing operators to manipulate it easily despite its actual size and weight. The pneumatic system effectively creates a counterweight that offsets the test head's mass.
Solution Approach 2:
The manual mechanical manipulation of heavy test heads is replaced by a pneumatic-hydraulic system. Instead of relying on operator strength to move the test head, the pneumatic cylinders provide the necessary force, substituting human mechanical effort with pressurized gas or liquid that can be easily controlled and adjusted.
3Manufacturing precision
If the test head is provided with six degrees of freedom for flexible docking, then the docking precision is improved, but the complexity of the manipulator system increases
Solution Approach 1:
The six degrees of freedom are segmented into three rotational degrees (pitch, roll, theta) and three translational degrees (X, Y, Z), each handled by separate mechanical subsystems. The manipulator is divided into multiple stages, each providing specific rotational or translational motion, allowing precise control of each degree of freedom independently while maintaining overall system manageability.
Solution Approach 2:
The manipulator system is designed with universal joints and compliant mechanisms that can accommodate various docking configurations. The same basic manipulator structure provides multiple degrees of freedom through a standardized set of joints and linkages, reducing overall complexity compared to having separate specialized mechanisms for each degree of freedom.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables the test head to be maneuvered in a compliant, weightless state across multiple degrees of freedom, reducing the physical effort required for operators and accommodating various peripheral orientations and heights, enhancing the efficiency and versatility of test head docking operations.
Implementation Method 1
pneumatic cylinders to provide compliant motion in the vertical direction. In such a design, the vertical stroke provided by the test head manipulator is limited by the stroke of the pneumatic cylinder arrangement
Implementation Method 2
a combination of support structures and compliant mechanisms, including pneumatic cylinders and spring systems
Data Source
AI summary
An apparatus (1) for manipulating a load includes a first support structure (60) for supporting the load and a second support structure (4) for supporting the load. The apparatus also includes a coupling (3) coupled between the first support structure (60) and the second support structure (4). The coupling (30) includes a compliant mechanism (340a) for providing a compliant range of motion to the load about a rotative axis where a center of gravity of the load is located away from the rotative axis. The rotative axis is a non-vertical axis.